Severe environmental contamination has resulted from the disposal of used apparatuses, including devices, instruments or appliances when such apparatuses contain metals in a form which can leach into the environment. Examples of such apparatuses are listed in Table 1.
TABLE 1Apparatus ExamplesApparatusSolubilized Metals Lead-acid batteriesLeadRechargeable Ni—Cd batteriesCadmium, nickelOther Ni—Cd batteriesCadmium, nickelAlkaline-manganese batteriesMercury, zincNickel-zinc batteriesNickel, zincNickel-metal hydride batteriesNickelIron electrode batteriesNickel, silverZinc-carbon batteriesMercury, zincMercuric oxide batteriesMercurySilver oxide batteriesCadmium, silver, zincVanadium batteriesVanadiumMercury switchesMercuryMercury thermostatsMercuryFluorescent lighting tubesMercuryMercury vapor lampsMercuryMetal halide lampsMercurySodium lampsMercurymercury instruments and appliancesMercuryElectronic        circuitryArsenic, beryllium, cadmium,silverTreated woodArsenic, chromiumSemiconductorsArsenic, cadmium, seleniumSolar photovoltaic cellsArsenic, cadmium, selenium
Many types of apparatuses, such as those listed in Table 1, are manufactured which contain solubilized metals at some point during their use, storage or disposal. Each type of apparatus raises specific concerns regarding the manner in which contamination may enter the environment. Manufacturers of these apparatuses are coming under increasing pressure from new environmental regulations. Increasing regulation is also bringing about an increase in recovery and recycling of soluble metals from such apparatuses. Each type of apparatus has its own characteristic patterns of manufacture, use and recovery.
Lead-acid batteries have often been segregated from other waste for disposal. Facilities have been established to crush the batteries and reclaim the elemental lead. However, such batteries may leak during storage prior to disposal. Also, lead-acid batteries contain sulfuric acid, which is capable of dissolving the lead. As a result of these problems, it is common for the recycling sites to have contaminated soil and ground water, resulting in the need for expensive environmental remediation at such sites.
The lead-acid battery industry is a major consumer of lead in the United States. Starting-lighting-ignition (SLI) lead-acid batteries are primarily employed in transport vehicles (e.g. cars, trucks, buses, planes, golf carts, etc.) and as an emergency source of power. According to the Battery Council International (BCI), an industry organization, SLI battery production in the U.S. averaged approximately 100 million units per year from 1994 through 1997. This consumed an estimated 70% of the annual U.S. lead production or some 1.08 million metric tons per year.
Recycling lead from spent SLI batteries, referred to as secondary lead, is a major source of the annual production of lead. Currently, about 68% of the yearly U.S. consumption of lead is from secondary sources, the majority of which (about 90%) is from recycled SLI batteries. In 1997, in the U.S., 30 plants were actively engaged in the production of secondary lead.
A 1996 study by the BCI estimates a SLI battery recycle rate in the U.S. of approximately 98%. The 2% which is not recycled is likely discarded as municipal solid waste (MSW). Even if the recycling percentage in the U.S. is as high as 98%, the 2% not recycled could represent some 22,000 metric tons per year of lead impacted materials being improperly disposed of and accessible to pollute the environment. Greenpeace, an environmental organization, estimates that only 80% to 90% of spent lead-acid batteries were recycled in the U.S. as of 1993.
Some studies indicate that about 138,000 tons, or 65%, of the lead found in the municipal solid waste stream comes from lead-acid batteries. When improperly disposed of, lead-acid batteries can corrode and release soluble lead and lead contaminated sulfuric acid into the environment, which in turn can pollute lakes, rivers, streams, ground water and eventually drinking water. In the event that lead-acid batteries are incinerated, lead will be released into the air and/or remain in the ash; in either case, a potentially dangerous environmental condition exists.
Rechargeable nickel-cadmium (Ni—Cd) batteries are ubiquitous in modern society as power sources for a wide variety of articles such as cellular and cordless phones, camcorders, CD players, laptop computers and cordless power tools. The number of Ni—Cd batteries produced each year may be in the hundreds of millions in the U.S. alone.
When initially introduced, Ni—Cd batteries were typically and inadvertently disposed of in MSW. However, in 1996, in the U.S. a Federal law, The Mercury Containing and Rechargeable Battery Act (Public Law 104-142) was enacted to facilitate the efficient recycling of rechargeable Ni—Cd batteries, as well as to restrict the manufacture and use of certain mercury-containing batteries. Title I of that Act establishes uniform national labeling requirements for Ni—Cd batteries, small sealed lead-acid batteries, and certain other regulated batteries. Each battery or battery pack must bear a recycling symbol and recycling phrase appropriate to its electrical chemistries. Recovery of the metals in Ni—Cd batteries is currently conducted at only one facility in the United States. While these initiatives are a partial solution, they are not the total answer. Currently, it is estimated that the recycling rate for Ni—Cd batteries is only about 15%.
Over the last decade the consumption of mercury has been steadily decreasing due in part to the pressure to avoid disposing of mercury products into the environment. This has also resulted in greater recycling of mercury. In the United States, establishment of land disposal restrictions on mercury-containing waste has made secondary sources more cost effective than primary sources, in contrast to other nations where primary mercury is still predominantly used. Title II of the Mercury-Containing and Rechargeable Battery Act phases out the use of most batteries containing mercury as a base chemical or additive. Title II of that Act also phases out the use of most alkaline-manganese and zinc carbon batteries containing intentionally added mercury and button cell mercuric oxide batteries. Other mercury oxide batteries will be allowed with certain limitations.
The total amount of mercury use in the United States is declining, although there is still a large amount used, generally in small increments, in a variety of apparatuses. The amount of mercury in each apparatus is generally quite small. Typically, a thermometer contains 0.5 g to 3 g, thermostats 3 g, mercury switches 3.5 g, and fluorescent lights 10 mg to 40 mg.
Previously, soluble-metal-containing devices, such as those listed in Table 1, have often been included in (MSW) disposal, a practice which may pollute the ground water in the vicinity of the municipal landfills.
Various approaches have been developed to bring about the environmental remediation of metal-contaminated sites, including remediation of sites contaminated with various apparatuses that contain soluble metals in a form which can leach into the environment. In some cases, the contaminated soil is removed to a secure landfill, where protection is obtained by placing the soil between layers of synthetic liner materials. The United States Environmental Protection Agency (U.S. EPA) has developed treatment requirements for such materials, which require that the leaching of the metals must be controlled prior to placement in land fills. In other cases, on-site treatment of the soil is used to render the soil nonhazardous by EPA standards. After on-site treatment, depending on environmental regulations, contaminated soil may be reused or disposed of in a nonhazardous waste landfill. Ground water contamination at these sites may be addressed by extraction wells, treatment systems, and reinjection of the treated ground water. Various treatment approaches have been developed for treatment of the soils and ground water.
There is a need for systems to ameliorate leaching of soluble metals from various types of metal-containing apparatuses. Such apparatuses have the potential to cause environmental damage when solubilized metals are released into the environment.
Environmental regulations in some countries have established both test procedures and concentration limits for the metals. In the event that wastes containing these metals exceed the limits, the wastes may be considered hazardous under the relevant regulations. The U.S. EPA has promulgated an acid extraction procedure for use in classifying wastes: the Toxicity Characteristic Leaching Procedure (TCLP, described in EPA SW-846 Method 1311, incorporated herein by reference). Universal Treatment Standards (UTSs, described in the Land Disposal Restriction Requirements Draft Phase IV rule, incorporated herein by reference) have been promulgated, including lower leaching limits and a more complete list of metals of concern. Other leaching procedures are also used in the evaluation of soluble metals. In particular, the U.S. EPA has developed the Synthetic Precipitation Leaching Procedure (SPLP, described in EPA SW-846 Method 1312, incorporated herein by reference) which utilizes synthetic rainwater rather than the stronger extraction fluids which are used in the TCLP.
Table 2 summarizes the existing TCLP limits and the promulgated UTS limits for solubilized metals in soils and other non-wastewaters. Such limits are set out merely as examples and may change from time to time and may differ from one jurisdiction to another.
TABLE 2Leaching Limits (mg/l)Metal (Symbol)Existing TCLPPromulgated UTSArsenic (As)5.05.0Antimony (Sb)—1.15Barium (Ba)10021.0Beryllium (Be)    —1.22Cadmium (Cd)1.00.11Chromium (Cr)5.00.60Lead (Fb)5.00.75Mercury (Hg)0.20.025Nickel (Ni)—11.0Selenium (Se)   1.05.7Silver (Ag)5.00.14Thallium (Ti)—0.20Vanadium (V)—1.6Zinc (Zn)—4.3
Those skilled in the art will understand that other soluble metals may require environmental control, such as radioactive metals, including radioactive cobalt, uranium, plutonium, americium, thorium, cesium and strontium.
Fixation reagents have previously been incorporated into a variety of polymeric matrices, such as ion-exchange matrices, that are resistant to release of the fixation reagent. Such matrices are typically resistant to degradation, and may be intended for long term use in aqueous environments. For example, U.S. Pat. No. 4,239,865 discloses a polyvinyl(dialkylthiocarbamoylthio) acetate resin, in which the fixation reagent is incorporated into the polymer, which is said to be insoluble in water or benzene. Similarly Canadian Patent No. 972,498 discloses covalently-modified heavy-metal-binding resins obtained by reacting nitrogen groups on the resin with carbon disulfide. Zinc sulfide has also been suggested for use as a metal-binding agent in a water-insoluble hydrophilic matrix, as disclosed in U.S. Pat. No. 4,280,925. Matrices that are insoluble in water, but soluble in stomach acid, have been suggested for specialized use as a coating for lead paint, with the disclosed intention that such coatings will remain on the paint and not release the fixation reagents unless the paint is ingested, in which case the metal-binding agents will leach out of the matrix to bind lead so that it is not poisonous. Water-insoluble films of polyvinyl alcohol that have been cured with borax are disclosed for such applications in U.S. Pat. No. 4,112,191.